JP2011520590A - Particles with bipolar position-specific features and their preparation process - Google Patents

Abstract

  The present invention relates to particles having bipolar position-specific features and processes for their preparation. It is an object of the present invention to provide particles with bipolar position-specific features on the surface that have two spatially specific sites whose surface features are not identical. Particles prepared by regiospecifically treating an asymmetric clay precursor having an organyl or organoheteryl group attached to one coordinating cation on a surface sheet produce two spatially specific particles whose surface characteristics are not identical. It has been found to provide particles with bipolar position-specific features having sites on the surface.

Description

  The present invention relates to particles having bipolar position-specific features and processes for their preparation.

  Any discussion of prior art throughout the specification should not be considered as an admission that the prior art is widely known or forms part of the common general knowledge in the field. .

  Particles having an asymmetric distribution of exposed surface chemical groups are said to have a great many applications in a variety of fields. Such asymmetric particles require a substantially high energy supply to desorb from the liquid-liquid or gas-liquid interface, and as a result, such particles are dependent on concentration or content of particles and the particles. In terms of the lifetime of the emulsion formed, it is expected to be more efficient as an emulsion and / or foam stabilizer compared to particles with isotropically distributed surface chemical groups. Such asymmetric particles have the ability to orient themselves in an electric / magnetic field and are used for dual functionality purposes or in stimuli-responsive devices to build a block for ultra-specific assemblies, etc. Is expected to be used when

  The schemes for synthesizing particles with such bipolar surface characteristics can be broadly classified into two categories: (a) monolayer methods and (b) bulk methods.

  The monolayer method is a regioselective surface modification method in which one half of the homogeneous particles are protected and a controlled reaction is performed on the exposed surface. The reported scheme is (i) temporarily masking the other hemisphere while modifying the surface of one hemisphere, and (ii) reacting so that the surface is protected by particles shielding the surface. (Iii) performing microcontact printing, and (iv) assuming that the particles cannot rotate during the procedure and partially contacting the reactive medium at the interface. is there.

  Typically, in a monolayer approach, particles with anisotropically distributed surface chemical groups are prepared by regioselective surface modification from precursor particles that do not have surface anisotropy. An example of the design and synthesis of such particles using the above scheme is described in the review of [1]. One approach that has been used in the past is disclosed in U.S. Patent No. 5,099,037 (Th. Goldschmidt AG, 1987), which includes particles to stabilize or destabilize emulsions of less than 100 microns in size. A fragment containing a hydrophilic group on one side and a hydrophobic group on the other side so that the hydrophilic and hydrophobic groups are anisotropically distributed in a non-statistical manner. Particles are described. One way to obtain such fragments is by sharing hollow microspheres. In any of the described methods, the precursor material has a homogeneous distribution of surface groups such as silica, alumina, hollow microspheres, microgels, carbon and starch. A process starting from asymmetric particles such as 1: 1 clay is not described.

  Furthermore, single layer methods for preparing such asymmetric particles typically begin by aggregating precursor particles at the gas-liquid, liquid-liquid or solid-gas interface. The particles at the interface are then regioselectively processed from one side of the interface. Therefore, the scale-up of such a method is limited by what interface regions can occur. Furthermore, the rotation of particles at the interface needs to be suppressed in order to ensure the position selectivity of the treatment.

A few bulk methods have been reported to synthesize particles with bipolar surface characteristics. In one approach, preformed core-shell nanoparticles are phase separated and simultaneously or subsequently chemically reacted with one component. For example, silver-silica (Ag—SiO ₂ ) core-shell nanoparticles undergo a reaction with molecular iodine, which is a strong oxidizer for silver. As a result, the silver core is phase-separated from the shell while adhering to the silica shell, forming snowball-like particles. In another example, nanoparticles with bipolar surface features have been synthesized based on the controlled nucleation and growth of a single particle on the surface of the precursor. In another example, supramolecular particles (dendrimers) have been synthesized using a bottom-up approach, and macromolecules possessing a fractal-like organization have been synthesized.

  However, in conventional bulk methods, the yield of particles with bipolar surface characteristics is relatively low, and such methods are only suitable for laboratory scale preparation. Furthermore, conventional methods are relatively more expensive. There is no reliable method that can be adapted to produce particles with bipolar position-specific features on a large scale in a cost-effective manner.

  On the other hand, several methods for producing an organoclay or an organic-inorganic hybrid material using clay as a precursor material are known. However, there are no reports on the bipolar surface characteristics of such organically modified clay particles.

  Non-Patent Document 2 describes the synthesis of a grafted derivative of kaolinite. Kaolinite's internal surface hydroxyl group is esterified with alcohol and begins with clay intercalated with dimethyl sulfoxide. In these processes, it is essential to use preliminarily intercalated kaolinite. Non-Patent Document 3 describes that the surface between kaolinite layers is organically modified by transesterification using propanediol. Methoxy-modified kaolinite is used as a starting material and reacted with propanediol to prepare hydroxypropoxy-modified kaolinite. These prior art documents describe 1: 1 clay as a starting material. However, grafting agents are small organic molecules of less than 4 carbon atoms and thus the resulting particles do not have hydrophilic and hydrophobic groups that are anisotropically distributed in a non-statistical manner.

  Other literature reports coating of inorganic particles such as clay particles. For example, in documents such as Patent Document 2 or Patent Document 3, such a coating can be polar or non-polar depending on the material of the coating. In these publications, the clay simply acts as a support. Another example of a disclosure for coated particles is US Pat. No. 6,057,037, which discloses clay particles (kaolinite), which are first coated with an organic diamine and then with a fatty acid, Provided are hydrophobic, organophilic particulate materials that can be applied generally in organic non-polar media and intermediate polar materials. Such treatment makes the particles suitable for use in non-polar media, but the particles are not suitable for use in polar materials because they cannot be dispersed in polar media. Appropriate.

U.S. Pat. No. 4,715,986 British Patent No. 867,752 EP 927,748 US Pat. No. 3,211,565 US Pat. No. 3,211,556

Perro, J. et al. Material Chem. 2005, 15, pages 3745-3760 Gardolinski and Lagary, Clay Minerals, 2005, 40, 537-546 Itagaki and Kuroda, J Material Chem. 2003, 13, 1064-1068. B. P. Binks, Europhys Lett, 1991, 16, 53 B. P. Binks, Curr, Opin, Colloid, Interface Sci, 2000, 7, 21 B. P. Binks, J Phys Chem Chem Phys, 2000, 2, 2959

  In view of the limitations in the prior art, one of the objects of the present invention is to overcome or improve at least one of the disadvantages in the prior art, or to provide a useful alternative.

  Another object of the present invention is to provide particles having bipolar position-specific features on the surface that have two spatially specific regions whose surface features are not identical.

  Yet another object of the present invention is a bipolar having two spatially specific regions on the surface, one of the specific surfaces being hydrophilic and the other specific surface being hydrophobic. It is to provide particles with position specific features.

  Yet another object of the present invention is to provide particles with bipolar position-specific features that can be emulsified at relatively low concentrations.

  Yet another object of the present invention is to provide particles with bipolar position-specific features that can provide a relatively more stable emulsion at relatively low particle content.

  Yet another object of the present invention can be used to produce on a large scale particles with bipolar position-specific features that have two spatially specific regions on the surface whose surface features are not identical. Is to provide a reliable manufacturing process.

  Yet another object of the present invention is to provide particles having properties similar to those of high HLB surfactants suitable for use in preparing oil-in-water emulsions.

  It is known that nano-sized or micro-sized particles can stabilize an emulsion and form a surfactant-free emulsion. However, such emulsions require a relatively high content of solid particles. Furthermore, the emulsion is not relatively stable.

  The inventor unexpectedly found that particles prepared by regiospecifically treating asymmetric clay precursors having organyl or organoheteryl groups attached to one coordination cation of the surface sheet have surface characteristics. It has been found to provide particles with bipolar position-specific features that have two spatially specific regions on the surface that are not identical.

  According to the present invention, the precursor is asymmetric 1: 1 or 2: 1: 1 clay particles, the clay particles have alternating tetrahedral and octahedral sheets, and one external surface plane is a tetrahedral sheet. Coordination terminated with another external surface plane terminated with an octahedral sheet and a chemical group having more than 3 carbon atoms and selected from organyl or organoheteryl groups on one outer side of the surface sheet Particles with bipolar position specific characteristics attached to the cation are provided.

According to another aspect of the invention, the precursor is asymmetric 1: 1 or 2: 1: 1 clay particles, the clay particles have alternating tetrahedral and octahedral sheets, and one external surface plane is A process for preparing particles having bipolar position-specific features, terminated with a tetrahedral sheet and another external surface plane terminated with an octahedral sheet comprising:
a. Treating the precursor with a mineral acid;
b. Raising the pH above 8 by adding alkali;
c. Adding an alkali metal salt of a C10-C22 carboxylic acid at a temperature of 50 to 150 ° C .;
d. Lowering the pH below 7 by adding mineral acid;
e. Separating a solid product comprising particles having bipolar regiospecific characteristics;
A process is provided.

It is a difference spectrum of Fourier transform infrared (FTIR) of (A) kaolinite, (B) silica, and (C) alumina. All three particles reacted with oleic acid according to the invention. FIG. 2 is an X-ray spectrum of untreated kaolinite particles and regioselectively treated particles of the present invention, showing that no difference has occurred in the space between layers. In the drawing, regioselective samples are indicated as TS and indicated by the left Y-axis scale, while untreated particles are indicated as UT and indicated by the right Y-axis scale.

[precursor]
Precursors of particles with bipolar position-specific features according to the present invention preferably have asymmetric tetrahedral and octahedral sheets, the outer surface planes terminating with tetrahedral and octahedral sheets 1: 1 or 2: 1: 1 clay particles. 1: 1 clay particles are particularly preferred as the precursor.

  Preferred 1: 1 clays in the present invention include kaolinite and serpentine subgroup minerals. The species contained in the kaolinite subgroup are kaolinite, dickite, halloysite and nacrite. Particular preference is given to 1: 1 clays of the kaolinite subgroup, ie selected from kaolinite, dickite, halloyside or nacrite.

  The species contained in the serpentine subgroup are chrysolite, lizardite, and amesite.

  The preferred 2: 1: 1 clay in the present invention comprises a chlorite group of minerals. Chlorite is also called 2: 2 clay by some mineralogists. Chlorite, like 2: 1 clay, includes tetrahedron-octahedron-tetrahedron sheets with a layer of particularly weakly bonded talc between the tetrahedron layers.

  The tetrahedral sheet preferably contains silicon coordinated tetrahedral cations. The tetrahedral sheet may also contain coordinated tetrahedral cations substituted for the same tangible material other than silicon. Coordinated tetrahedral cations that are tangibly substituted include, but are not limited to, aluminum, iron or boron cations.

  The octahedral sheet preferably comprises a coordinated octahedral cation of aluminum. The octahedral sheet may also contain coordinated octahedral cations substituted for the same tangible material other than aluminum. Coordinatingly octahedrally coordinated octahedral cations include magnesium or iron cations.

  The chemical group is preferably attached to a coordinating cation on one outer side of the outer face sheet. Thus, the chemical group is attached to the coordinating cation on the outer side surface of the tetrahedral sheet. Alternatively, the chemical group is attached to a coordinating cation on the outer side surface of the octahedral sheet. According to a preferred embodiment, the chemical group attached to the coordinating cation on the outer side surface of the tetrahedral topsheet is not identical to the chemical group attached to the coordinating cation on the outer side surface of the octahedral topsheet, Coordination cations on the outer side of each of the tetrahedral and octahedral topsheets are attached to the chemical group.

  The chemical groups are preferably not attached to coordinating cations that are not on the surface of the tetrahedral or octahedral sheet, or on the inside of the surface sheet.

[Organyl or organoheteryl group]
As used herein, the term organyl group means any organic substituent having one free valence at a carbon atom, regardless of the type of functional group. The term organic substituent includes any chemical group containing one or more carbon atoms.

  As used herein, the term organoheteryl group means any monovalent group containing carbon having a free valence at an atom other than carbon. The term organoheteryl group includes organosilyl and organosiloxanyl chemical groups. According to a preferred embodiment, the organoheteryl group is attached to the coordinating cation by filling the free valence at an atom selected from oxygen, nitrogen, sulfur, phosphorus or silicon.

The chemical group has more than 3 carbon atoms, preferably —R, —O—R, —SO ₄ —R, —N (X ₁ ) —R, —O—PO ₃ (X ₁ ) —R. , —O—C (O) —R, —Si (X ₁ X ₂ ) —R, and —O—Si (X ₁ X ₂ ) —R, wherein X ₁ and X ₂ are H, — (CH _{2) n -CH 3, Cl,} Br, selected from the group consisting of I, n is 0 to 15, -R is an organyl group.

According to the present invention, the organyl or organoheteryl group is attached to a coordinating cation on one outer side of the face sheet. It is envisioned that more than one organyl or organoheteryl group can be attached to one of the topsheets. Organyl or organoheteryl groups may be attached to the coordination cations of the tetrahedral topsheet. Alternatively, the organyl or organoheteryl group may be attached to the coordination cation of the octahedral surface sheet. After a chemical group is attached to the coordinating cation on one outer side of the topsheet, the coordinating cation on the outer side of the other topsheet is attached to the second chemical group. The second chemical group can be any chemical moiety. Preferably, the second chemical group is selected from inorganic chemical groups or organyl or organoheteryl chemical groups. Some non-limiting examples of the second chemical group include —NO ₃ , —NH ₃ , —SO ₃ , —SO ₄ , —CH ₃ , and —CH ₂ —CH ₃ .

  Preferably, the coordination cation of the tetrahedral topsheet is attached to an organoheteryl group, which is a silane having a free valence in oxygen.

[Particles with bipolar position-specific characteristics]
Particles having bipolar position-specific features with surface chemical groups that are anisotropically distributed due to the attachment of organyl or organoheteryl groups to the coordination cations of the tetrahedral or octahedral surface sheet Has at least one spatially specific region on the surface with different surface characteristics. Particles having bipolar position-specific features may have two specific regions on the surface whose surface features are not identical. Particularly preferably, the particles have two spatially specific outer faces whose surface features are specific. By selecting specific organyl and / or organoheteryl groups and selectively attaching them to the coordination cations of the tetrahedral and / or octahedral surface sheets, various types of anisotropic characteristics can be obtained at bipolar positions. It is envisioned that it can be applied to the surface of particles having specific characteristics. Surface feature anisotropy or asymmetry includes, but is not limited to, hydrophobicity, electrical charge density, color, fluorescence, piezo response, and magnetic properties.

[Particles with anisotropic hydrophobicity]
Preferably, the particles have two spatially specific outer surfaces with specific surface features, one of the specific outer surfaces being hydrophilic and the other of the specific outer surfaces being hydrophobic. Have.

The —R group is —R ₁ and any one of the parent molecules in the form of X ₃ —R ₁ has a surface energy in the range of 10-60 ergs / cm ² , X ₃ is H, OH, phenyl, Selected from O—CH ₃ , Cl, Br or I. Without being limited by theory, the surface energy of the parent molecule X ₃ -R ₁ is 10 to 60 ergs / cm ² , and the organoheteryl group containing the organyl group —R ₁ or —R ₁ is one of the surface sheets. When attached to a coordinating cation, it is considered that hydrophobic characteristics are selectively imparted to the surface of particles having bipolar position-specific characteristics.

Or, the —R group is —R ₂ , and any one of the parent molecules in the form of X ₃ —R ₂ has a partition coefficient or logD value of less than or equal to zero at pH 7 and X ₃ is H , OH, phenyl, O—CH ₃ , Cl, Br or I.

  As used herein, the term LogD refers to the equilibrium concentration of all kinds of molecules (non-ionized and ionized) in octanol at the given temperature, usually 25 ° C., and the same kind in the aqueous phase. It means the ratio to the equilibrium concentration of the molecule. LogD differs from LogP, where ionized species are also considered as the neutral form of the molecule.

According to a preferred embodiment, the coordinating cation on the outer side surface of one surface sheet is attached to a chemical group in which —R is —R ₁ , and the coordinating cation on the outer side surface of the other surface sheet is It is attached to the group in which —R is —R ₂ .

  Preferably, the organyl or organoheteryl group has more than 3, more preferably more than 8, most preferably more than 20 carbon atoms. Without being limited by theory, it is believed that surface hydrophobicity increases with increasing number of carbon atoms. The number of carbon atoms in the organyl or organoheteryl group is preferably 8-30, more preferably 10-22, most preferably 12-18, or even 14-18.

  The use of small organyl or organoheteryl groups is not preferred because these groups are so small that they can be bound not only on the outer surface but also inside the space between the layers. Bonding to the interior of the space between the layers occurs especially in the case of organyl or organoheteryl groups having 3 or fewer carbon atoms.

  Particles according to the present invention in which one surface has hydrophobic properties and the remaining surface has hydrophilic properties, the particles aggregate at interfaces such as gas-solid, gas-liquid, liquid-liquid and solid-liquid interfaces. It is useful in some applications that involve doing. The particles with bipolar position-specific features of the present invention are particularly useful for stabilizing foams and emulsions.

  These particles are particularly suitable as a substitute for high HLB surfactants, regardless of whether the particles are first suspended in the oil phase and then in the water phase or vice versa. Can be formed. Particles having only one polarity, either polar or nonpolar (such as untreated clay or organoclay, respectively) will result in an emulsion in which the particles are initially dispersed in the continuous phase ( As reported in Non-Patent Document 4). Without being bound to any particular theory, for molecular surfactant systems, the nature of the emulsion formation depends on the degree of filling, and then the degree of filling determines the nature of the emulsion's curvature. It is known that The loading of the molecular surfactant at the interface is a function of the hydrophobic and hydrophilic groups on the molecule and is usually expressed as a hydrophilic / lipophilic balance (HLB) number. A surfactant with a high HLB number will always result in an oil-in-water emulsion to maximize contact of the water phase with its large hydrophilic groups. Thus, the molecular geometry plays an important role in determining the properties of the emulsions formed by these surfactants.

  On the other hand, the particles of the present invention can be envisioned to be high particle HLB surfactant analog particles due to their inherent geometry. As a supplementary explanation, the size of these particles is preferably 100 to 1000 nm, preferably 400 to 600 nm in the XY dimension, and the Z direction is 100 to 500 nm, preferably more than 150 nm but less than 250 nm. After reacting with the fatty acid, one of the surfaces is modified to become hydrophobic. The size (i.e. thickness) of this hydrophobic layer resulting from the reaction with fatty acids depends on the length of the fatty acid tail. For example, C18 fatty acids typically give a thickness of about 2-3 nm (calculated based on the linear organization of hydrocarbon groups). As a result of this, one of the side surfaces of the particle has a very thin hydrocarbon layer, while the other particles remain hydrophilic. This is a geometry similar to a high HLB surfactant system, and this geometry is, by theory, a factor in becoming an oil-in-water emulsion regardless of the initial wettability of the particles. .

The particles with bipolar position-specific features of the present invention provide a relatively more stable emulsion compared to untreated particles at the same particle content and require a relatively low particle content to obtain a stable emulsion And is useful as an emulsifier. Other advantages of emulsions obtained using the particles of the invention are:
a. Relatively high tolerance for the presence of electrolytes,
b. The flexibility to carry more non-aqueous active ingredients because a relatively large number of oil phases can be blended into an oil-in-water emulsion without sacrificing the feel,
c. Relatively high viscosity and yield stress compared to untreated particles at the same particle content,
d. Including the formation of emulsions at relatively low concentrations of surfactants, and the possibility of making surfactant-free emulsions.

  According to another aspect of the present invention, there is provided an oil-in-water emulsion comprising water, oil, and particles having the bipolar position specific characteristics of the present invention. The particles having bipolar regiospecific characteristics are preferably 0.1-99%, more preferably 1-30%, most preferably 1-15% by weight of the emulsion.

  The regioselectively selected particles according to the present invention provide a relatively more stable gas-liquid foam.

[Particles with anisotropic color]
The —R group is —R ₃ and any one of the parent molecules in the form of X ₃ —R ₃ has at least one absorption peak at wavelengths between 200 nm and 700 nm in polar or nonpolar solvents. Particles with bipolar, position-specific color characteristics can advantageously be used as sensors for investigating dispersed phase impurities.

[Particles with anisotropic fluorescence]
The -R group is R ₄ and any one of the parent molecules in the form of X ₃ -R ₄ has at least one emission peak at a wavelength of 200 nm to 700 nm in a polar or nonpolar solvent.

[Particles with anisotropic electric charge density]
The —R group is —R ₅ and any one of the parent molecules in the form of X ₃ —R ₅ has a resistivity greater than 0.1 μohm cm.

[Particles with characteristics of anisotropic piezo reaction]
The -R group is -R ₆ and any one of the parent molecules in the form of X ₃ -R ₆ is 1,2, m, 222, mm2,4, -4,422,4mm, -42m, 3 , 32, 3 m, 6, −6, 622, 6 mm, −62 m, 23, and −43 m.

[Magnetic properties]
The —R group is —R ₇ and any one of the parent molecules in the form of X ₃ —R ₇ is paramagnetic or diamagnetic.

  Some preferred examples of particles with bipolar position-specific features according to the present invention are shown below.

[process]
Any chemical reaction or series of reactions in which the precursor is asymmetric, such that the organyl or organoheteryl chemical group is selectively attached to the coordinating cation on either the outer side of the tetrahedral or octahedral surface sheet When it is a clay, it can be used to prepare particles with bipolar position-specific characteristics according to the invention. The selectivity of the reaction is an essential feature. Any chemical reaction or series of reactions in which the same organyl or organoheteryl group is attached to the coordinating cations of both, i.e., octahedral and tetrahedral topsheets, is excluded from the scope of the present invention.

  It will be appreciated that one skilled in the art will be able to prepare particles having the bipolar regiospecific characteristics of the present invention by selectively attaching organyl or organoheteryl chemical groups to one coordinating cation of the surface sheet. Or a series of reactions may be selected.

  Grignard reagents or organolithium compounds can be used as reactant deposits of organyl groups on the coordination cations of the tetrahedral topsheet.

According to one aspect, a process for preparing particles having bipolar position-specific characteristics, comprising:
a. Treating the precursor clay with a mineral acid;
b. Raising the pH above 8 by adding alkali;
c. Adding an alkali metal salt of C10-C22 carboxyoxy acid at a temperature of 50 to 150 ° C .;
d. Lowering the pH below 7 by adding mineral acid;
e. Separating a solid product comprising particles having bipolar regiospecific characteristics.

  The carboxylic acid preferably has 8 to 30 carbon atoms, more preferably 12 to 18 carbon atoms, and most preferably 14 to 16 carbon atoms. The carboxylic acid according to the present invention may be saturated or unsaturated. Unsaturated acids are particularly preferred. Some non-limiting examples of carboxylic acids that can be used include oleic acid and linoleic acid.

  In this reaction, the organoheteryl group (a fatty acid having a free valence in oxygen) is attached to the coordination cation of the octahedral sheet.

(Example)
The invention will be illustrated using examples. The examples are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[Example 1: Behavior of emulsion]
(Process for preparing regioselective particles)
Kaolinite was used as a precursor. 1 gram of kaolinite (laboratory grade kaolinite, eg Loba) is added to 100 ml of 0.1N hydrochloric acid (eg Emerck) and the mixture is added to a bath sonicator (eg Elma Transsonic 460 / H sonicator). ) For 15 minutes. Following this, 0.4 g of sodium hydroxide pellets were added while the mixture was constantly stirred by a tabletop magnetic stirrer. After dissolution of the sodium hydroxide pellets, the pH of the system was measured using a pH meter (eg, Orion, model # 720A) and found to be 11.5. Excess sodium oleate (purity 99%, eg Loba) was added to the reaction mixture to a concentration of 90 g / l. The reaction mixture was constantly stirred at 90 ° C. for 2 hours and held overnight (12 hours) to equilibrate. The system pH was then adjusted to 6.5 by dropwise addition of 1N HCl in order to convert unreacted soap to its free fatty acid. In order to remove traces of unreacted soap, the reaction mixture was centrifuged and the precipitated clay was washed repeatedly with water and acetone. To obtain particles with bipolar regiospecific characteristics, the reacted clay is dried in a hot air processor at 55 ° C. for 2 hours. Of course, the process of the present invention does not depend on the area of the interface and is therefore relatively easy to scale up.

  The particles of the present invention were further compared to the coated particles disclosed in the prior art. The coated clay (kaolinite) material disclosed in US Pat. The material was further used in the following experiments.

[Determining the characteristics of regioselectively processed particles]
(Infrared measurement)
Independent reactions following the same procedure as described above were similarly carried out using alumina (chromatographic grade, eg S. D Fine-chem) and silica (Aerosil 200, eg Degussa) instead of kaolinite. . Aerosil 200 (eg, Degussa) and chromatographic grade alumina, Al ₂ O ₃ (eg, S. D Fine-chem) were used as exemplary silica and alumina surfaces, respectively. The difference IR spectrum of the three substrates is shown in FIG.

Next, the spectrum obtained from Kaolinite and Alumina shown in Figure 1, -COOH vibration peak of oleic acid in 1710 cm ^-1, the I magnitude of a new set of 1550～1570Cm ^-1 and 1460～1470Cm ^-1 Replaced by a peak. An asymmetric stretch around 1650-1550 cm ⁻¹ and a symmetric stretch band near 1400 cm ⁻¹ are characteristic of carboxylate anions. This indicates that a new aluminum oleate compound was formed on both the kaolinite and alumina surfaces via the carboxylate anion. It has also been found that the two new peaks obtained for both kaolinite and alumina are located close to each other, which is on the surface of both -COOH in oleic acid and alumina or kaolinite. This suggests that a bidentate carboxylate complex or cross-linked (—COO—Al + 3) environment was formed with Al + 3.

In addition to the peaks described above, another new set of peaks appears between 2950-2850 cm ⁻¹ for kaolinite and alumina. These peaks are characteristic of C—H stretching. Asymmetric and symmetric stretching of the methylene group occurs around 2926 and 2853 cm ⁻¹ , respectively. The position of these bands does not vary more than ± 10 cm ⁻¹ in the aliphatic hydrocarbon series. The appearance of peaks at 2917 and 2849 cm ⁻¹ for kaolinite and 2924 and 2953 for alumina are derived from the methylene group of the hydrocarbon chain of oleic acid. This further indicates that the reaction has indeed occurred on both the alumina and kaolinite surfaces. On the other hand, the reacted silica shows an uncharacteristic spectrum. The stretching frequencies of both the carboxylate anion and methylene are not present, especially in the case of silica. This indicates that silica was not involved in the reaction with oleic acid. Therefore, in the above-described process, the organoheteryl group (a fatty acid having a free valence in oxygen) is attached to the coordination cation of the octahedral sheet, that is, aluminum.

[Emulsification research]
(Preparation of emulsion and evaluation of emulsion stability)
0.1 g of particles were placed in a calibrated 50 mL Tarson centrifuge tube and 5 ml of deionized water (Millipore) was added therein. The mixture was sonicated in a sonicator bath (SS Microsonics) for 45 minutes. 5 ml of LLPO (light liquid paraffin oil, supplied by Raj Petrochemicals) was then added to the water-particle mixture and the resulting mixture was homogenized at about 6500 rpm for 10 minutes using an Ultra Turrax T25 homogenizer. The volume of emulsified oil was recorded first and after 24 hours. Accelerated stability testing was performed by subjecting the emulsion to low speed and high speed centrifugation (LSC and HSC). Centrifugation was carried out in a Remi centrifuge at about 500 rpm for 1 minute (LSC) and an additional 4000 rpm for 1 minute (HSC). The volume of emulsified oil was recorded after LSC and HSC.

  Emulsions were prepared using a particle concentration of about 2% by weight of the emulsion and about 49% oil and water, respectively, of the emulsion. The emulsion was aminosilane treated, obtained from particles with bipolar regiospecific characteristics of the invention (Example 1), unreacted kaolinite (Comparative Example 1-A), organoclay (English India China Clay). Produced using Amshine-Kaolinite (Comparative Example 1-B) and hydrophobic silica (Degussa Aerosil R974) (Comparative Example 1-C) treated with hydrous clay .

  Emulsions with untreated particles and organoclays are relatively unstable, while emulsions with relatively stable hydrophobic silica are extremely difficult to form as hydrophobic silica due to their small particle size And potentially harmful to the respiratory system and cannot be easily handled. Furthermore, since it is hydrophobic, it is extremely difficult to form an emulsion by mixing silica. From the results, it is clear that the particles with the bipolar position-specific features of the present invention impart relatively high stability to the emulsion while at the same time being easy to handle and process.

[Stability of emulsion in the presence of electrolyte]
Emulsions were formed using varying concentrations of electrolyte and particles with bipolar position-specific characteristics according to the invention (Examples 2-4). Comparative Examples 2-A to 4-A were identical to Examples 2 to 4 except that untreated clay particles were used instead of particles having bipolar position specific characteristics.

  From the results, it can be determined that the particles with bipolar position-specific features according to the present invention form an emulsion that can tolerate the presence of relatively much electrolyte.

[Stability of emulsion in the presence of surfactant]
All of the following examples have a particle content of 1% by weight of the emulsion. Both oil and water are about 49.5% by volume of the emulsion. The surfactant is 1% by weight of the emulsion.

  It has already been shown that in the absence of surfactants, emulsions can be formed using particles having the bipolar regiospecific characteristics of the present invention. From the above results, the emulsion formed using the particles having the bipolar position-specific features of the present invention when the particles are of the same content is the corresponding emulsion formed using the untreated particles. It is clear that it is relatively more stable than

[Types of oil that can be emulsified]
Emulsions were prepared using a particle concentration of about 2% by weight of the emulsion and about 49% oil and water, respectively, of the emulsion. Emulsions were obtained from the particles with bipolar position-specific features of the present invention (Examples 8 and 9), unreacted kaolinite (Comparative Examples 8-A and 9-A), organoclay (English India China Clay). Amshine Kaolinite treated with hydrosilane treated with aminosilane (Comparative Examples 8-B and 9-B) and hydrophobic silica (Degusa Aerosil R974) (Comparative Examples 8-C and 9-C). Generated using. The oil used and its surface tension are shown in the table below together with the results regarding the stability of the emulsion.

  From the results it is clear that the particles with bipolar position-specific features according to the present invention provided an emulsion with oils having a wide range of surface tension values. Emulsions made with particles with bipolar position-specific features of the present invention are relatively more stable compared to emulsions made using prior art particles.

[Viscosity of emulsion]
An emulsion was prepared using 10% by weight of the emulsion particles with bipolar regiospecific characteristics and about 45% oil (light liquid paraffin oil) and water, respectively, of the emulsion (Example 10). Comparative Example 10-A corresponding to Example 10 was made using untreated particles.

  Emulsions were made in test tubes. The test tube was then placed in a horizontal position and the amount of emulsion that flowed out of the test tube and the amount remaining in the test tube was recorded after 15 minutes. The results are shown in the table below.

  The results show that emulsions made using particles with the bipolar position-specific features of the present invention have a relatively high yield stress and viscosity compared to emulsions made using the corresponding untreated particles. It is clear that it has the following characteristics.

[Form generation and stability]
Foam generation and stability were evaluated for foams generated using particles with bipolar regiospecific characteristics (Example 11) and untreated particles (Comparative Example 11-A). Foam was prepared by adding 2 g of particles to 10 mL of deionized water and stirring the mixture for 10 minutes at 6400 rpm in a high speed homogenizer (Ultratrax make). The initial volume of the foam was measured after stopping the stirring (t = 0). Furthermore, the volume of the foam was also measured at t = 15 minutes. The results are shown in the table below.

  The results show that the particles having the bipolar position-specific features of the present invention can generate a relatively large volume of foam compared to untreated particles, and further provide a foam with relatively high stability. Obviously you can.

Example 2: Comparison of homogeneous and bipolar particles As explained above, particles that are ideally bipolar will behave like particulate analogs of surfactants. For this reason, it is expected not to exhibit a state depending on the dispersion medium as described above. Verification of whether the particles are bipolar or homogeneous after the experiment was carried out.

[Experiment protocol]
0.1 g of particles were placed in a calibrated 50 mL Tarson centrifuge tube and 5 ml of deionized water (Millipore) was added therein. The mixture was sonicated in a sonicator bath (SS Microsupersonics). Then 5 ml of LLPO (light liquid paraffin oil, supplied by Raj Petrochemicals) was added to the water-particle mixture and the resulting mixture was homogenized at about 6500 rpm for 10 minutes using an Ultra Turrax T25 homogenizer.

  In another set of experiments, instead of first dispersing the particles in the aqueous phase, the particles were dispersed in oil and then water was added. Other procedures are the same.

In both cases, the oil phase was doped with the fluorescent dye Nile Red (2.24 10 ⁻⁶ mM) to determine the nature of the continuous phase. It was confirmed that the characteristics of the oil phase such as surface tension (0.05 mNm-1) did not change even when this small amount of dye was added. Fluorescence microscopy was used to determine the phase properties.

[result]
Fluorescence micrographs of these four systems are given below (Table 7). From these micrographs it is observed that the emulsion formed by the particles of the present invention is always an oil-in-water emulsion regardless of the initial wettability of the particles.

  On the other hand, emulsions formed with unreacted particles and particles prepared using U.S. Patent No. 6,057,038 exhibit phase inversion depending on the initial wettability of the particles. This behavior due to unreacted particles and other homogeneous particles is similar to observations made previously in Non-Patent Document 6 and the difference in the contact angle the particles encounter when approaching the interface from two different phases. That is, it can be explained in consideration of contact angle hysteresis. When homogeneous particles approach the interface from the oil phase, the homogeneous particles encounter an advancing contact angle (measured into the water), while receding when the homogeneous particles approach the water phase. A contact angle is established (measured from the water phase).

  The particle size characteristics of the present invention were about 500 nm or less in the XY dimension and about 200 nm or less in the Z direction. After reaction with oleic acid, one of the surfaces becomes denatured and hydrophobic due to the presence of an oleic acid layer of about 2 to 3 nm or less (calculated based on the linear organization of hydrocarbon groups).

  As a result of this, one of the side surfaces of the particle has a very thin hydrocarbon layer, while the other particles remain hydrophilic. This is a geometry similar to a high HLB surfactant system, and this geometry is probably a factor in becoming an oil-in-water emulsion regardless of the initial wettability of the particles.

  As shown in the table above, the particles according to the invention are started by first suspending the particles in water and then mixing with the oil phase or first hanging in oil. Regardless of the emulsification process that becomes cloudy and then mixed with water, an oil-in-water emulsion is formed. Untreated particles or coated particles (similar to the particles of Patent Document 4) form an emulsion with a continuous phase, which is the phase in which the particles are first dispersed.

  This shows that the raw and coated particles disclosed in the prior art are homogeneous rather than bipolar, whereas the particles according to the invention are truly bipolar.

(Example 3: spacing d)
X-ray diffraction measurements (eg, Siemens D500) were performed to show that organyl or organoheteroyl groups are present only on the outer surface and not in the interlayer space.

  The particles used were the regioselective particles of Example 1 and untreated kaolinite clay.

  To examine the degree of intercalation of oleic acid inside the clay lattice, X-ray diffraction measurements were performed on the reacted clay sample to undesirably intercalate oleic acid during the reaction. I investigated.

  Intercalation increases the interplanar spacing d in kaolinite, which is typically 7.4 mm. An X-ray diffraction pattern of reacted kaolinite and unreacted kaolinite is presented in FIG. A d001 peak characteristic of raw kaolinite is observed at 2θ = 12.6 ° (very dark, sharp and narrow), which is generally known to be unique to kaolinite. Corresponds to 0.74 nm. No difference is observed between the unreacted particles and the particles of the present invention, indicating that there is no oleic acid intercalation at the interplanar spacing d.

Claims (18)

  The precursor is asymmetric 1: 1 or 2: 1: 1 clay particles, the clay particles having alternating tetrahedron and octahedron sheets, one outer surface plane terminating in the tetrahedron sheet; A coordinating cation in which the outer surface plane is terminated with the octahedral sheet and a chemical group having more than three carbon atoms and selected from organyl or organoheteryl chemical groups is on one outer side of the surface sheet Attached particles with bipolar position-specific features.   The particle having bipolar position-specific features according to claim 1, wherein the chemical group is attached to a coordinating cation on an outer side surface of a tetrahedral topsheet.   The particle having bipolar position-specific features according to claim 1, wherein the chemical group is attached to a coordinating cation on the outer side surface of the octahedral topsheet.   On the condition that the chemical group attached to the coordinating cation on the outer side surface of the tetrahedral surface sheet is not the same as the chemical group attached to the coordinating cation on the outer side surface of the octahedral surface sheet, the tetrahedron and 4. Particles with bipolar position-specific features according to any one of claims 1 to 3, wherein the coordinating cations on the outer side of each of the octahedral topsheets are attached to the chemical group.   5. The method according to claim 1, wherein the organoheteryl group is attached to the coordination cation by satisfying a free valence at an atom selected from oxygen, nitrogen, sulfur, phosphorus, or silicon. Particles having the described bipolar position specific characteristics. The chemical group is —R, —O—R, —SO ₄ —R, —N (X ₁ ) —R, —O—PO ₃ (X ₁ ) —R, —O—C (O) —R, — Selected from Si (X ₁ X ₂ ) —R and —O—Si (X ₁ X ₂ ) —R, —R is an organyl or organoheteryl group, and X ₁ and X ₂ are H, phenyl, — (CH ₂ ) _n— CH ₃ , Cl, Br, I, or —R selected from the group consisting of an organyl or organoheteryl group which may or may not be the same, wherein n is 0 to 15. To 5 having a bipolar position-specific feature.   The particle having bipolar position-specific characteristics according to claim 6, wherein the chemical group has more than 8 carbon atoms. -R is -R ₁ and any one of the parent molecules in the form of X ₃ -R ₁ has a surface energy in the range of 10 to 60 ergs / cm ² , and X ₃ is H, OH, phenyl, _{-CH 3, O-CH 3,} Cl, selected from Br or I, the particle with bipolar topospecific characteristics according to any one of claims 1 to 7. -R is -R ₂ and any one of the parent molecules in the form of X ₃ -R ₂ has a partition coefficient or log D value of less than or equal to zero at pH 7 and X ₃ is H, OH Particles with bipolar position-specific features according to claim 1, selected from: phenyl, —CH ₃ , O—CH ₃ , Cl, Br or I. The coordinating cation on the outer side surface of one surface sheet is attached to the chemical group with -R being -R ₁ , and the coordinating cation on the outer side surface of the other surface sheet is -R is -R _2. 10. A particle having bipolar position-specific features according to claim 8 or 9, attached to a group that is   11. A particle with bipolar position-specific features according to any one of claims 1 to 10, wherein the particle has two spatially specific outer faces with specific surface features.   12. A particle having bipolar position-specific features according to any one of claims 1 to 11, wherein one of the specific outer faces is hydrophilic and the other of the specific outer faces is hydrophobic. Any one of the parent molecules wherein -R is -R ₃ and is in the form of X ₃ -R ₃ has at least one absorption peak at a wavelength of 200 nm to 700 nm in a polar or non-polar solvent; X ₃ is H, OH, _{phenyl, -CH 3, O-CH 3} , Cl, selected from Br or I, the particle with bipolar topospecific characteristics according to any one of claims 1 to 12 . Any one of the parent molecules wherein -R is R ₄ and is in the form of X ₃ -R ₄ has at least one emission peak at a wavelength of 200 nm to 700 nm in a polar or non-polar solvent; ₃ is H, OH, _{phenyl, -CH 3, O-CH 3} , Cl, selected from Br or I, the particle with bipolar topospecific characteristics according to any one of claims 1 to 13.   A particle having a bipolar position-specific characteristic, wherein the coordination cation of the tetrahedral surface sheet is attached to an organoheteryl group which is a C10 to C22 carboxylic acid having a free valence in oxygen.   A particle having a bipolar position-specific characteristic, wherein the coordination cation of the tetrahedral surface sheet is attached to an organoheteryl group which is a silane having a free valence in oxygen.   17. A particle having bipolar position specific characteristics according to any one of claims 1 to 16, wherein the 1: 1 clay is selected from kaolinite, halloysite, dickite or nacrite. The precursor is asymmetric 1: 1 or 2: 1: 1 clay particles, the clay particles having alternating tetrahedron and octahedron sheets, one outer surface plane terminating in the tetrahedron sheet; A process for preparing particles having bipolar position-specific features, wherein the outer surface plane of the ends terminates in the octahedral sheet,
a. Contacting the precursor with a mineral acid;
b. Raising the pH above 8 by adding alkali;
c. Adding an alkali metal salt of a C10-C22 carboxylic acid at a temperature of 50 to 150 ° C .;
d. Lowering the pH below 7 by adding mineral acid;
e. Separating a solid product comprising particles having bipolar regiospecific characteristics;
Including processes.